Raise on some HTTP status codes

[dccunha]

What?

Implements the proposal #454

Why?

When you use httparty in many different projects it starts to become tedious to add a verification on every request. To accomplish this, you have to do something like this:

module Api
  class Base
    include HTTParty

    def get(path, options = {})
      raises_unless_success { self.class.get path, options }
    end

    private

     def raises_unless_success
      httparty = yield
      fail HTTParty::Error, "Code #{httparty.code} - #{httparty.body}" unless
        httparty.response.is_a?(Net::HTTPSuccess)
      httparty
    end

  end
end

I believe this is not a straight solution.

My idea

module Api
  class Base
    include HTTParty
    raise_on (400..599).to_a

    def get(path, options = {})
      self.class.get path, options
    end
  end
end

[jnunemaker]

I actually don't like automatic raising of exceptions and prefer explicitly checking errors in each case, but I have a feeling that many users of httparty will like this and it is optional, so I'm going to merge. Thanks for the PR!